Hello from MrBillDoesMath!
Answer: 21
Discussion:
The two triangles are similar as the corresponding angles are equal. So let's look at the ratios of the corresponding sides.
PB / RX = (2x -1 ) / (x -2)
and PB/RS = 14/6
Let's solve for x in
(2x-1)/(x-2) = 14/6.
Multiple both sides by (x-2) and then by 6. This gives
6 (2x-1) = 14 (x-2) or
12x - 6 = 14x -28 or subtracting 12x from both sides
-6 = 14x -12x - 28 or adding 28 to both sides
28-6 = 2x so
22 - 2x and x = 11
But PB = 2x -1 of 2(11) -1 = 21.
Regards, MrB